Imagine an alien world teeming with exotic organisms; verdant ecosystems and advanced megafauna.
On this planet life emerged twice, billions of years ago. Present day, roughly half of plants and animals are of carbon-based descent (as an example), the other half stem from silicon-based ancestors (as another example).
Crucially, on this planet carbon-based life cannot consume silicon-based life for nourishment, nor vice versa.
My question is, with the above in mind, what unique ecological worldbuilding would be possible for these dual biospheres; what adaptations, niches and other interesting features could emerge for life on this planet that wouldn't be possible for the homogenic biosphere on earth?
This is not an idea I've seen elsewhere, so I'd love to hear ideas for fleshing out this concept. :)
Edit: To clarify, the specifics of biochemistry isn't important. The core of the question is how the ecology could be different if half/plants and animals could not gain nutrients from the other half of animals/plants. If unclear, assume organisms analogous to earths'.